Thermoformable sole

ABSTRACT

The invention relates to a device ( 1 ) for forming an insole, able to be introduced into a shoe. It also relates to a shoe equipped with such a device. This device ( 1 ) comprises: two modules ( 2, 3 ) made of thermoformable material which is flexible, elastic and fluid-tight, such as to gas, liquid or gel, said modules consisting of at least one cavity ( 6, 7 ) able to contain said fluid; at least one channel ( 8 ) connecting at least two cavities. At least one duct ( 11 ) is arranged on the module in order to inject into or evacuate from the cavity a quantity of fluid, such as gas, liquid or gel ( 16 ) located inside the cavity.

The invention relates to a device to be used as part of a sandal, thong or flip-flop which can be thermoformed in a microwave oven. The invention will be produced by footwear manufacturers, and is intended for podiatrists who provide custom plantar orthoses, or for end users or customers after reading the instructions for the device.

The device of the invention concerns the field of orthopedics, particularly plantar orthoses which use corrective insoles tailored to the foot to compensate for walking problems in persons having plantar disorders of various origins, or simply to improve comfort when walking. Such a plantar orthosis can be used by men or women of any age who have any of a variety of foot problems. It may also be worn by people having no physical issues but who want a more comfortable shoe.

In a known manner, a plantar orthosis is a custom-made orthopedic insole designed to be inserted or slid into a shoe. It allows restoring the biomechanics of the foot by supporting and balancing a flat, hollow, or deviated foot and properly aligning the joints. It also relieves painful pressure and reduces muscle tension to improve foot comfort and slow foot deformations. This orthosis can be applied to all or part of the plantar surface. In addition, it helps decrease side effects such as calluses, corns, toe deformation, bunions, and heel pain.

These plantar orthoses are custom-molded from a positive mold or directly on the foot, depending on the material used. The material and the production technique are chosen based on the age, activities, and disease of the customer or patient. The manufacture of such plantar orthoses first requires taking an impression of the foot of the client or patient, using a block or box of deformable foam to form a negative mold of the foot, then creating a positive model, meaning a solid object accurately representing the shape of the foot, obtained after pouring and hardening plaster in said negative mold. This positive model is then refined or modified to maximize its effectiveness during the orthosis preparation. There is a distinction between plantar prostheses that are rigid, semi-rigid, or flexible; their manufacturing techniques are well-known to a person skilled in the art and all use such positive models. These different techniques are time-consuming and require professionals, specifically prosthetists or podiatrists, who must also make final adjustments to the prosthesis when the patient tries it on. When the obtained result is unsatisfactory or unsuccessful, it is then necessary to construct a new prosthesis.

In another known technique, the plantar prosthesis is designed from a thick sheet of thermoformable material, often polyethylene or EVA, from which a sole is cut out according to a template. The obtained sole is placed on a block of deformable foam. The foot is placed directly on the previously heated sole, causing the sole to be reshaped on this block of foam. The sole then cools, its material hardening to retain the impression of said foot. This sole now corresponds to the shape of the foot, providing a negative impression of the foot. Next more material must be added to the bottom of this sole, often the same material, and the lower portion sanded so that the sole will lie flat within the shoe. This sole construction completely replaces the insole of the shoe. The creation of such a prosthesis requires considerable work and the skills of the professional prosthetist or podiatrist, given that after cutting the sheet and thermoforming the sole, the prosthesis often requires further adjustment by such specialists.

These various techniques are also difficult to implement on open or ventilated shoes such as sandals or flip-flops.

The invention is intended to overcome the disadvantages of currently existing prostheses. For this purpose, the invention relates to a device (1, 20) for forming an insole for footwear, consisting of a thickness of thermoformable material comprising at least one system containing at least one cavity (6, 7, 22, 23) configured inside the thickness of thermoformable material, and at least one duct (11, 12, 13, 14, 30) connected directly or indirectly to the at least one cavity and connecting to the outside of the thickness of thermoformable material, at least one heatable fluid at least partially filling said at least one cavity of said at least one system. The device is constructed of said thermoformable material which is impermeable to said at least one fluid. In said device (1), said at least one system comprises a plurality of cavities (6, 7) forming at least one group of at least one cavity (6, 7), each group of more than one cavity comprising at least one channel (8, 9, 10), each channel being configured to connect two cavities (6, 7) and allow the passage of the heatable fluid, at least one duct (11, 12, 13, 14) being connected to at least one cavity (6, 7) of each of the groups. The system comprises at least one cavity (22, 23), said at least one cavity being dotted with nubs or spikes (25). The thickness of thermoformable material consists of two superimposed modules (2, 3) assembled together, said at least one system being configured in at least one of the two modules. The device may comprise at least two systems separated by a wall (15) impermeable to said at least one heatable fluid. The heatable fluid is chosen from among gases, liquids, and gels, that are microwavable. The thermoformable material is chosen from among polyethylene, ethylene vinyl acetate, or a combination of the two. The footwear, comprising an outer sole, additionally comprises a device (1, 20) for forming an insole, said device resting on said outer sole. The footwear may comprise an upper configured to allow introducing the device (1, 20) inside said footwear. The footwear may comprise an upper that is open or closed.

The invention relates to a device for forming an insole, able to be introduced into or be a part of open or closed footwear, in order to form a plantar prosthesis providing correction or improved comfort which is thermoformed in the microwave oven. This device comprises one or more layers of thermoformable material, of a certain density and/or a certain hardness, identical or different. Inside the device are created, in one or more layers of thermoformable material—by mechanically hollowing them out, molding the material, or any other technique resulting in cavity creation—a certain number of cavities of identical or different shapes and sizes, connected to each other by a channel or channels of identical or different cross-section, shape, and length. The cavities have two important roles: they contain a microwavable fluid or gel which is heated in a microwave oven, and they weaken the thermoformable material so that it is more compressible. These cavities may be located inside the device in a manner that targets specific areas for compression. Channels preferably connect each cavity, allowing the circulation of the microwavable fluid or gel between cavities. These cavities connected by these channels form a network. In the device, there may be several networks of cavities and channels separated by a wall impermeable to the microwavable fluid or gel. Each network of cavities and channels is connected to the outside of the device by one or more ducts in order to permit a fluid to enter the device and also exit from it. This or these ducts to the outside are of identical or different sizes and cross-sections according to the nature of the fluid or gel. These ducts are only necessary in cases where the thermoformable material is impermeable to the fluid. In the case where the thermoformable material is permeable to the fluid, particularly to ambient air which is microwavable, said material naturally constitutes said ducts connected to each of the cavities. These cavities may be intended to be partially or completely filled, using the channel or channels connecting them together and the ducts connecting them to the outside, with a microwavable fluid or microwavable gel or more simply the ambient air because air contains water vapor. The device is heated by agitating the water molecules contained in the fluid, gel or air. When the device is heated in the microwave oven, the fluid, gel or air contained in the network of cavities and channels will heat, and by conduction will also heat the thermoformable material to permit reshaping the material and therefore reshaping the device. When a foot is placed on the device, the weight of the user has the effect of compressing and crushing the thermoformable material because of its weaker structure due to the cavities, channels, and any ducts to the outside to allow fluid to flow out of the device if the material is impermeable. If the thermoformable material is permeable to the fluid and gel, only the cavities are necessary to weaken it, as the fluids can flow out of the device due to the permeability of the material.

The device of the invention allows taking an impression of the foot, retaining the impression, trying it out, and repeating this multiple times if it does not exactly meet customer requirements. To achieve this, either the device is ready for use, meaning the manufacturer previously filled the device with a certain amount of microwavable fluid or microwavable gel, or the user fills the device himself or herself with a certain amount of microwavable fluid or microwavable gel recommended by the manufacturer, using one or more ducts connecting one or more networks of cavities and channels, or the device is used as is because it already contains a certain volume of air inside it. Then the user places the device in the microwave for the time and power settings indicated by the manufacturer for the composition of the fluid or gel contained in the device. At the end of heating period, the device is placed on smooth or flat ground or on an appropriate foam block and the user then places his foot with full weight on the device, meaning while he is standing, in order to reshape the device and mold it to his foot; it is then possible to make a correction until complete satisfaction is achieved. If the foot is overly or insufficiently corrected, the operation is simply restarted, as the device reassumes its initial form when reheated in the microwave oven. This operation can be performed by a person who has received appropriate training; this may be a professional or a customer following the manufacturer's instructions.

In one embodiment, the device consists of several layers of sheets of polyethylene and/or EVA of identical or different density and hardness, hollowed out to provide one or more networks of channels and cavities which weaken the materials to allow better deformation of the device when the weight of the body is applied, giving an accurate impression of the foot. These cavities may be located in one or more component layers of the device and may be in certain targeted areas of the device to facilitate deformation of the device in these areas. Ideally, these cavities are located at the foot pressure points (heel, lateral arch, ball, and toes) in order to allow the device to adapt properly to each person's foot. The network or networks of cavities and channels connected by one or more ducts to the outside of the device allow the microwavable fluid or gel to spread appropriately through the device, which means a more uniform heat when the device is heated in the microwave oven. The cavities, channels, and ducts form a system. The cavities may be of variable sizes within the same system or from one system to another. The channels may be of variable lengths and cross-sections within the same system or from one system to another. The ducts may be of variable lengths and cross-sections within the same system or from one system to another. Each system has at least one duct to the outside of the device to allow the escape of water vapor emitted when heated in the microwave oven, in order to avoid damage to the device. Ideally and for aesthetic reasons, it is possible to have only one duct to the outside, placed on the device to connect a large network of cavities and channels, or a multitude of ducts, microperforated using needles, connecting one or more networks of cavities and channels. A cavity may be connected directly by one or more ducts; in this case each cavity of the device is connected to the outside by at least one duct.

Such a device has the advantage of good heat distribution within the device so that it molds properly to the foot, good elimination of the water vapor released by heating in the microwave oven, and also good elimination of heat to avoid “burning” the user. It is also possible to heat the device without microwaves by injecting a hot fluid, not necessarily microwavable, inside the system or systems of cavities, channels, ducts.

The invention also relates to footwear comprising a sole and a upper, said footwear being equipped with a device for forming a plantar prosthesis or insole which is introduced inside the upper and rests on the insole of said footwear.

The invention also relates to footwear that is a ski boot comprising a bootee and a shell, said boot being equipped with a device for forming the bootee or a part of the bootee, said device being introduced inside the shell of the ski boot.

In one embodiment of the footwear, the device is removable from it.

This footwear may have a closed upper, particularly a street shoe such as a dress shoe or athletic shoe, or an upper that is open or ventilated by means of a plurality of openings arranged along its edge, such as a sandal.

Other features of the invention will be apparent from reading an embodiment of a device according to the invention, which is based on the following figures:

FIG. 1 diagrams a cross-sectional longitudinal view of a first embodiment of the device of the invention;

FIG. 2 diagrams a cross-sectional top view of a second embodiment of the device of the invention.

In the embodiment illustrated in FIG. 1, the device 1, which is used to create an insole for a shoe, boot, sandal, or flip-flop, consists of two sheets of thermoformable material 2, 3 or modules 2, 3, having the shape of a sole as illustrated in FIG. 2, manufactured of a flexible and elastic material impermeable to fluids, such as EVA (ethylene-vinyl acetate). Module 2 has been processed to create two independent systems 4, 5, separated from each other by an impermeable wall 15, these two systems comprising cavities 6, 7, of different dimensions, channels 8, 9, 10 of different dimensions, and ducts 11, 12, 13, 14, of different dimensions. Module 3 is attached onto module 2 so that it covers the two systems. These modules 2, 3 comprise the shape of a sole, as illustrated in FIG. 2 for the second embodiment. These modules 2, 3 form the device 1. In addition, this device 1 is able to retain a fluid 16; to achieve this the material of these modules 2, 3 is also impermeable to said fluid. Preferably, EVA is used to construct these two modules 2,3.

This device is used to form two systems 4, 5, according to the embodiment illustrated in FIG. 1, preferably of different volumes. These systems 4,5, are arranged at strategic locations usually requiring correction to the sole of the foot; however, a number of different systems may be provided to refine the correction at specific strategic locations.

Preferably, a gel fluid 16 is placed in system 4 and ambient air in system 5.

These systems 4,5, are implemented using a separating wall 15.

In the embodiment illustrated in FIG. 1, the device 1 comprises four ducts 11, 12, 13, 14, arranged on the module 2. Duct 11 connects the cavities 6 and the channel 8 to the outside of the device, for example at its rear. Ducts 12, 13, 14, connect the cavities 7 and channels 9, 10 to the outside. Ducts 11, 12, 13, 14, are of different dimensions; only ducts 12, 13 are identical. Channels 8, 9, 10 are of different dimensions. System 4, consisting of the cavities 6, the channel 8 and the duct 11, is partially filled with fluid 16. System 5, consisting of the cavities 7, the channels 9, 10, and the ducts 12, 13, 14, is filled with ambient air.

Preferably, the fluid 16 injected or eliminated by the duct 11 in system 4 is water or a water-based gel; however, it is possible to use gas or even liquids appropriate for use in a microwave oven and for the component elements of the device 1. The injection or elimination is done by a means appropriate for the fluid, in order to control the amount of fluid inside the device 1. In the case of water or gel, a syringe is used, for example.

In the variant embodiment illustrated in FIG. 2, the device 20 comprises two sheets of flexible, elastic thermoformable material that is impermeable or fluid-tight to the fluids as used in the first embodiment illustrated in FIG. 1. The first sheet is, for example, constructed of a material identical to that of the modules 2, 3 of the first embodiment illustrated in FIG. 1 and is cut to obtain the shape of a sole or module 21 to be placed in the footwear. The second sheet is attached to the first sheet as in the first embodiment illustrated in FIG. 1. In this module 21, the thermoformable material is hollowed out to create a large cavity 22 dotted with small nubs 25 of EVA resembling dots or spikes and another smaller cavity 23 also dotted with nubs 25 of EVA, the two being separated by a permeable wall 24. In this embodiment illustrated in FIG. 2, the sizes of the dots or spikes of EVA are identical but the volume of these cavities can be increased or decreased to obtain more or fewer nubs and/or nubs of different sizes.

This module 21 consists of two systems 22, 23, dotted with nubs and separated by a wall 24 impermeable to fluids. Cavity 23 is preferably connected by four channels 26, 27, 28, 29 to cavity 22, rendering the wall 24 permeable to fluids. A duct 30 is placed for example at the rear of the module 21, connecting cavity 22 to the outside. Cavity 23 is connected to the outside via cavity 22 and the duct 30. These two cavities 22 and 23 may be filled with a fluid such as liquid, gel, or simply ambient air, via the duct 30. The number and dimensions of the cavities, channels, and ducts may also vary.

In these different variants of the design, the user places a device 1, 20 filled with fluid in the microwave oven, heats the device according to the power level and time settings indicated by the manufacturer, puts the device inside a shoe, boot, sandal, or flip-flop, then places his foot on the device within the shoe, boot, sandal or flip-flop. The thermoformable material, weakened by the heat and the cavities, is compressed and flattened. The water vapor formed in the cavities when the device was heated is emitted out the ducts, reducing the volume of the device; the thermoformable material is then reshaped under the sole of the foot and molds appropriately to it. If an improper correction is obtained, the operation is restarted in a similar manner. In the invention, the device 1, 20 can be used in various types of footwear, whether open or closed, athletic or street shoes, or ski boots.

Other embodiments are possible without leaving the scope of the invention. It is possible, for example, for the device to be composed of a single cavity or even of more than two systems of cavities, channels, and ducts, depending on the use that is to be made of it, particularly if it is used solely for increased comfort or conversely for therapeutic purposes. It is also possible to imagine a device comprising several systems of cavities, channels, and ducts with an association of walls between these systems, some of them permeable to the fluid and the others impermeable to the fluid; in this case the number of ducts will depend on the number of permeable and impermeable walls between these systems. 

1-11. (canceled)
 12. The device for forming an insole for footwear, consisting of a thickness of thermoformable material comprising at least one system containing at least one cavity configured inside the thickness of the thermoformable material, and at least one duct connected directly or indirectly to the at least one cavity and leading to the outside of the thickness of the thermoformable material, at least one fluid at least partially filling said at least one cavity of said at least one system, said fluid being intended to be heated to enable deformation of the thermoformable material.
 13. The device according to claim 12, wherein said thermoformable material is impermeable to said at least one fluid.
 14. The device according to claim 12, wherein said at least one system comprises a plurality of cavities forming at least one group of the at least one cavity, each group of more than one cavity comprising at least one channel, each channel being configured to connect two cavities and allow the passage of the fluid, at least one duct being connected to the at least one cavity of each of the groups.
 15. The device according to claim 12, wherein said system comprises at least one cavity, said at least one cavity being dotted with nubs.
 16. The device according to claim 12, wherein said thickness of the thermoformable material consists of two superimposed modules assembled together, said at least one system being configured in at least one of the two modules.
 17. The device according to claim 12, comprising at least two systems separated by a wall impermeable to said at least one fluid.
 18. The device according to claim 12, wherein said fluid is chosen from among gases, liquids, and gels, that are microwavable.
 19. The device according to claim 12, wherein the thermoformable material is selected from polyethylene, ethylene vinyl acetate, and a combination of the two.
 20. Footwear comprising an outer sole, wherein said footwear comprises a device for forming an insole according to claim 12, said device resting on said outer sole.
 21. Footwear according to claim 20, comprising an upper configured to allow introducing the device inside said footwear.
 22. Footwear according to claim 21, wherein said upper is open or closed. 